Editing blocks giving errors

Hi
I have few sites build in C5 and they all using the same theme. I was trying to edit something on one of the site today and when I click on save, it gives me error popup saying "javascript disabled error" and 100's line of code.

I am using the same theme (nuron) for all the sites and all the sites giving me same errors.

I suspect your error is arising from the c5 core passing html (that would include javascript) back to the browser in a broken state. Perhaps missing tags or quotes, in a way that the dialog in the browser sees the javascript part as text, not as javascript.

If its not specific to saving just one block, I would look at any special block templates you have developed or provided by your theme, for things like mis-matched tags, unclosed quotes, or other poorly formed html.